Lovisa Adelaïde Ehrnrooth (17 January 1826 in Nastola – 31 May 1905 in Helsinki) was a Finnish feminist and writer. Adelaïde Ehrnrooth was among 16 children of an aristocratic family. Adelaïde was born to Gustaf Adolf Ehrnrooth, a hero of the Finnish War. John Casimir Ehrnrooth was her brother. Adelaïde Ehrnrooth never married, herself, and dedicated her life to helping the women and the poor.
She was the founder of the Finnish Women’s Association — the first society for women’s suffrage in Finland. She was also active in the Union Kvinnosaksförening (Women’s Cause Association) in 1884 and the years after 1892, till her death. Helena Westermark called her "Finland's first woman journalist."
Adelaïde Ehrnrooth proposed voting rights for women in 1869.